Process for preparing v. i.-improving agents



. 2,987,457 Patented June 6, 1961 2,987,457 PROCESS FOR PREPARING V.I.-IMPROVING AGENTS Robert 0. Bolt, San Rafael, James G. Carroll, Martinez, and James R. Wright, El Cerrito, Califi, assignors, by mesne assignments, to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Filed Nov. 12, 1957, Ser. No. 695,531- 6 Claims. (Cl. 204-162) This invention is directed to: a process of converting hydrocarbon materials of low molecular weight to polymeric hydrocarbon materials of high viscosity and capable of producing in low molecular weight hydrocarbons compositions having high viscosity indexes; In particular, this invention pertains to a process of transforming motor fuels to polymeric materials useful as viscosity index improvers.

It is generally known that the-irradiation of organic liquids by means of neutrons, X-rays, or gamma rays often increases the viscosity, which is due to polymerization, cross-linking, etc. However, this change in viscosity is usually accompanied by only a slight change in the viscosity-temperature coefiicient. Materials produced by this means have not been useful for improving the viscosity indexes of lubricating oils.

It is a primary object of this invention to set forth a process by which hydrocarbon materials of low boiling point can be converted to polymeric materials useful for improving viscosity-temperature characteristics of lubrieating oils.

In accordance with the invention described herein, itv has been discovered that viscosity index improving agents can be obtained by subjecting hydrocarbon materials of low boiling point to gamma radiation. Although it is well known in the art that irradiation of organic liquids increases the over-all viscosity of the irradiated organic fluid, it is not known that the irradiation of low molecular weight hydrocarbonsaccording to the process herein results in the formation of viscous liquids capable of imparting high viscosity indexes to liquids having lubricathydrocarbons (e.g., petroleum distillates) boiling predominantly in the range of about 0 C. to about 210 C. Such hydrocarbons include n-pentane, n-hexane, Z-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, n-heptane, 2-methylhexane, 2,2-dimethylpentane, 2,4-dimethylpentane, n-octane, Z-methylheptane, 2,2-dimethylhexane, 3,4-dimethylhexane, 2,2,3'-trimethylpentane, 2,2,4-trimethylpentane (isooctane), hexamethylethylene, n,-nonane,. 3- methyloctane, 2,2-dimethylheptane, 3,4-dimethylheptane, 3,3-dimethyloctane, 3,4-dimethylhexane, mixtures there; of, etc. These hydrocarbons of themselves or mixtures thereof may be subjected to gamma irradiation. Mixtures of these hydrocarbons appear in such compositions known as gasolines, naphthas, petroleum ether, etc.

The'light hydrocarbon materials may besubjected to gamma radiation at. temperatures below. the boiling point thereof at atmospheric pressures or' at higher temperatures under pressures above atmospheric. It ispreferred to use ambient temperatures or temperatures aboveambient temperatures at atmospheric pressures for a period of time suflicient to form the desired polymericmaterial. Exceptional results from thisprocess are obtained by subjecting a gasoline fraction to gamma radiation fora period of. time suflicient to give a, total dos-ageequiv alent to about 2.5 1O to 6.0x l0 roentgens...

The gamma radiation source used hereinwas the spent nuclear reactor fuel element facility. This. was located. at the Materials Testing Reactor, National Reactor Test-v ing Station, Idaho.

The degree of polymerization desired can be governed by the total amount of radiation given'to the light boiling hydrocarbon material. The longer the irradiation time, the greater the molecular weight and. the viscosities of the end products obtained. The important criterion here is thetotal radiation dosage;

The. formation of polymeric viscosity index improving agents by'subjecting hydrocarbon materials of low boiling point. to gamma radiation is illustrated by the data hereinbelow.

Table I presents the distillation characteristics; of hydrocarbon materials prior to irradiatiom Table I DISTILLATION DATAMIXTURES' OF HYDROOARBONS BEFORE IRRADIA'IION (TEMPERATURES IN Hydrocarbon Sample BoilingPoint F.) at Percent Fraction Distilled Initial I0 20 I 30 40 EP ing characteristics; that is, the slopesof the viscosity- Table- II hereinbelow sets forth the distillation chartemperature curves of the resulting lubricating oils have 55 acteristics of hydrocarbon materials obtained after subvalues no greater than about 0.5.

The low molecular weight hydrocarbon materials are jecting the above samples A, B, and C to gamma radiation.

Table II IRRADIATION (TEMPERATURES IN Hydrocarbon Sample Dosage, 10 1.

Boiling Point F.) at Percent Fraction Distilled Table III EFFECT OF GAMMA RADIATION N HYDROCARBON FRACTIONS Viscosity at 210 F., cs., and ASTM Slope Sample Original After Exposure to After Exposure to -4X10 r. r.

Viscosity Slope Viscosity Slope Viscosity Slope By comparing the data in Table III for the original hydrocarbon material with that of the irradiated hydrocarbon material, it is apparent that the gamma irradiation has resulted in the formation of excellent viscosity indeximproving agents.

Data illustrating other physical characteristics of the original hydrocarbon composition and the irradiated composition are set forth in Table IV.

Table IV Hydro- Total Den- Brocarbon Dosage, sity, mine 30 F. 77 F. 100 F. 210 F. Sample B r. No.

The compositions formed according to the'process of this invention are of themselves characterized as having high viscosity indexes. Since it is possible to use as the original reactant a low molecular weight, low-boiling hydrocarbon, the resulting solution obtained by treating such a low molecular weight hydrocarbon with gamma radiation has a viscosity-temperature curve of less than 0.5. In numerous instances it is beneficial to separate the polymeric material thus formed (i.e., the viscosity index improving agent) from the lower molecular weight fraction, and incorporate this high molecular weight component having outstanding viscosity-index characteristics in a lubricating oil composition of low viscosity index. The viscosity-temperature curve of the final lubricating oil 4 composition will have a slope of extremely low value and will have been markedly improved.

We claim:

l. A process for converting a low boiling hydrocarbon material to a composition containing a polymeric material, which composition is characterized by a high viscosity index, comprising subjecting a paraflin hydrocarbon material boiling predominantly in the range of about 0 C. to about 210 C. to gamma radiation equivalent to a total dosage of from about 2.5 X 10 roentgens to about 6.0)(10 roentgens.

2. A process for producing a polymeric viscosity index improving agent comprising subjecting a petroleum distillate boiling predominantly in the range of about 0 C. to about 210 C. to gamma radiation equivalent to a total dosage of from about 2.5 X 10 roentgens to about 6.0)(10 roentgens.

3. A process for producing a polymeric viscosity index improving agent comprising subjecting a petroleum distillate boiling predominantly in the range of about 0 C. to about 210 C. to gamma radiation equivalent to a total dosage of radiation from about 2.0 10 roentgens to about 6.0 10 roentgens to produce a composition which has a viscosity-temperature curve slope no greater than about 0.5

4. The process of claim 3, wherein said petroleum distillate is a gasoline fraction.

5. A process for producing a polymeric viscosity index improving agent comprising subjecting a petroleum distillate boiling predominantly in the range of about 0 C. to about 210 C. to gamma radiation equivalent to a total dosage of radiation of from about 2.5)(10 roentgens at temperatures below the boiling point of said distillate to produce a composition which has a viscosity-temperature curve slope no greater than about 0.5.

6. A process for producing a polymeric viscosity index improving agent comprising subjecting a petroleum distillate boiling predominantly in the range of about 0 C. to about 210 C. to gamma radiation equivalent to a total dosage of radiation from about 2.5 X 10 roentgens to about 6.0)(10 roentgens at ambient temperatures to produce a composition which has a viscosity-temperature curve slope no greater than about 0.5.

OTHER REFERENCES Martini Chemical and Engineering News, vol. 33, No. '"14 (April 4, 1955), pp. 1425 and 1428.

i Mincher: AEC, Summary of Available Data on Radiation Damage to Various Non-metallic Materials, April 2, 1952, pp. 3 and 5. 

1. A PROCESS FOR CONVERTING A LOW BOILING HYDROCARBON MATERIAL TO A COMPOSITION CONTAINING A POLYMERIC MATERIAL, WHICH COMPOSITION IS CHARACTERIZED BY A HIGH VISCOSITY INDEX, COMPRISING SUBJECTING A PARAFFIN HYDROCARBON MATERIAL BOILING PREDOMINANTLY IN THE RANGE OF ABOUT 0* C. TO ABOUT 210* C. TO GAMMA RADIATION EQUIVALENT TO A TOTAL DOSAGE OF FROM ABOUT 2.5X109 ROENTGENS TO ABOUT 6.0X109 ROENTGENS. 